ANDRZEJ KRAUZEIn June 2009, two male patients were independently admitted to the Heartland Regional Medical Center in northwestern Missouri with fever, headache, muscle pain, nausea, and diarrhea—all classic signs of ehrlichiosis, a common tick-borne disease in the region. Although both men reported having recently been bitten by ticks, blood and serum samples sent to microbiologist William Nicholson, chief of Pathogen Biology and Disease Ecology at the Centers for Disease Control and Prevention (CDC), came back negative for Ehrlichia chaffeensis, the disease-causing bacterium.
Nevertheless, Nicholson says, when the researchers plated the samples over a culture of canine tumor cells, they started to see signs of a pathogen. First, they noticed increased vacuole formation in the cells. “When we see that, within a day or two we usually see Ehrlichia,” Nicholson explains. But in this case, no Ehrlichia appeared, and the cells eventually began to fall apart. Then, the single layer of cells that lined the bottom of the flask started to detach earlier than normal—within 6–7 days, instead of 2 weeks. Nicholson and his colleagues continued to transfer the cells to fresh media, “and then it’d do it again,” he says. “That was an indication that we have something in there, we just can’t see it.”
After finding ...
